Optical apparatus comprise a plurality of optical components, which must be adjusted accurately relative to one another or to a chassis, so that the apparatus will have the desired properties. The optical components, such as the slit, grating and receiver of a spectrometer, are therefore typically disposed on an apparatus chassis or similar device by means of adjustable holders. Depending on the number of degrees of freedom required for adjustment, these holders are rather complicated in structure and therefore expensive. They also occupy space.
From published German patent application DE-OS No. 32 11 867, U.S. Pat. No. 4,496,416, it is known, in adjusting and mounting an optical component in an optical apparatus, to hold the optical component using an adjusting device that is not part of the apparatus and to adjust it using this device, and to join it to the apparatus after the adjustment operation by using a liquid or pasty substance which sets with only a slight change in volume, and later to remove the adjusting device. In this way, a space-saving configuration of the optical apparatus is achieved, and the holding means of the optical components is very simple and hence economical.
One disadvantage of this method is that the adjusting devices take up space during the mounting and adjusting operation, and so in optical apparatus that have a very small volume, these devices can be used only with considerable difficulty, if at all. Recently, however, spectrometers having a volume on the order of milliliters or less have gained increasing significance. In other optical apparatus, too, there has been a trend toward miniaturization for some time. This applies particularly to multiplexers and demultiplexers for fiber-optic communications.